Microorganisms are widely used for industrially producing a broad range of useful substances, including alcoholic beverages, certain types of foods such as miso and shoyu, amino acids, organic acids, nucleic-acid-related substances, antibiotics, sugars, lipids, and proteins. These substances also find diversified uses, including foods, pharmaceuticals, detergents, products for daily use such as cosmetics, and a variety of chemical raw materials.
In industrial production of useful substances by use of microorganisms, improvement of productivity is one major topic of interest, and one approach therefor is breeding of microorganisms through mutagenesis-or other genetic means. Recently, in particular, with advancement of microbial genetics and biotechnology, more efficient breeding of useful microorganisms is performed through gene recombination techniques, and in association therewith, host microorganisms for obtaining recombinant genes are under development. For example, Bacillus subtilis Marburg No. 168, which has already been confirmed to be safe and have excellent characteristics as a host microorganism, has been further improved.
However, microorganisms inherently possess diversified genes so that they can cope with environmental changes in the natural world, and thus, they do not necessarily exhibit high production efficiency of proteins or similar substances in industrial production, where only limited production media are employed.